Celtic's trip to Belfast on Friday marks the start of what has been annual summer tradition for the club in recent years; the UEFA Champions League qualifying gauntlet.

Brendan Rodgers' side face Linfield in a match that is sure to be dramatic, with no away fans allowed at Windsor Park and the home supporters sure to give the Bhoys a fiery reception.

We expect it'll have the feeling of a derby of sorts and while Celtic will be massive favourites to go through the tie over two legs, the Hoops can take nothing for granted.

Even if Celtic do successfully get past the Northern Irish outfit, there's plenty of dangers ahead and reasons to be a little bit worried about qualifying for the group stages for the second successive years.

The Hoops will be seeded throughout and if all goes well, qualification shouldn't be a problem but here are THREE reasons it might not be as easy as task as you'd think at first glance, for a team who are coming off such an epically successful season...

More defensive problems

As reported by the BBC, Celtic defender Dedryck Boyata will be out for up to three months after suffering medial knee ligament damage during their friendly with Czech side Slavia Prague at the weekend.

It's incredibly disappointing and it appears to have become the norm for Celtic to be going into qualifiers with some sort of defensive mishap denting their hopes.

Last season both Jozo Simunovic and Boyata were unavailable with the club having to rely on the likes of Efe Ambrose and Eoghan O'Connell to get them through some matches. Those two have now left the club and with Kolo Toure having not signed a new contract either, it leaves the Hoops with a real lack of options in the heart of defence.

Only Simunovic and Erik Sviatchenko are fit and while Kristoffer Ajer is making the transition to the position, you wouldn't say he is ready yet for high pressure European matches at the back. Should something happy to the Croat or the Dane then Celtic would be in a real pickle.

Will the Hoops go out and sign a new defender or will they risk heading through these tricky matches with just two fit defenders?

Competition is as fierce as ever

Let's be honest, Celtic should be disposing of Linfield with relative ease given the disparity in resources, players and coaches between the two clubs. It's a tie that the Hoops will likely breeze through but as Celtic fans will know, the gulf in quality between round two of qualifying and round three is massive.

Should they make it to the third qualifying round then ties against the likes of  Astana or Partizan Belgrade are a real possibility. Facing the champions of Kazakhstan or Serbia would never be described as easy and you may remember that last summer, Brendan Rodgers' side only squeaked through against Astana themselves, requiring a last minute penalty by Moussa Dembele in the second leg to see them through.

Beyond that round and things get even tougher with potential match-ups against BATE Borisov or Legia Warsaw, who famously beat the Hoops in qualifying under Ronny Deila before seeing the result reverse due to an ineligible player.

You could make the argument that Rodgers' outfit are much superior to twelve months ago and while that's true, we're expecting that if Celtic do reach the group stages again, it'll be by a very slim margin.

Early season blips laid bare this week

Celtic have received the ultimate reminder this week that for Scottish teams, these early rounds can be especially difficult due to how close the fixtures are to the previous season. The pre-season has been short and although the Hoops have played a few friendlies, they are nowhere near match fit.

Linfield's season followed a similar structure and timeline to Scotland, so it's not an issue next week but if they come up against a team who are in the middle of a summer season, it'll be especially difficult.

St Johnstone were humbled by such a team on Thursday night and while Rangers can't blame their shocking exit from European football on that, their result is another reminder that these smaller teams from across the continent can spring a big surprise.

Celtic showed they are streaks ahead of other Scottish teams last season but there's still a lesson there for Brendan Rodgers' side; take nothing for granted.